<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #app {
            width: 600px;
            margin: 40px auto;
            text-align: center;
        }
    </style>
    <script src="./js/vue.js"></script>
</head>

<body>
    <div id="app">
        <h2>当前计数器的值为:{{num}}</h2>
        <counter v-on:counter-add="num++"></counter>
    </div>
</body>
<script>
    Vue.component('counter', {
        template: '<button @click="add">计数器</button>',
        methods: {
            add: function () {
                this.$emit('counter-add')
            }
        }
    })

    const vm = new Vue({
        el: '#app',
        data: {
            num:0
        },
        methods:{
            handleAdd:function(){
                this.num++;
            }
        }
    })
</script>

</html>